The fate of photons absorbed by phytoplankton in the global oceanPublished online here. ​

Phytoplankton, which serve as an important food source in the ocean, use photosynthesis to turn sunlight into cellular fuel. This study reports that nearly twice as much of the sunlight energy captured by phytoplankton in the ocean is released as heat than is used to make food. The finding suggests that phytoplankton don't photosynthesize as efficiently as researchers had thought.

While 35% of the absorbed light was used for making food to fuel the phytoplankton’s growth, nearly 60% of the light was converted to heat. In laboratory studies with nutrient conditions encouraging phytoplankton growth, the team observed the opposite result: Around 65% of absorbed light was used to make cellular fuel, while less than 35% was lost as heat. The team blames phytoplankton’s inefficient photosynthesis in the ocean on nutrient-poor waters, which cover 30% of the world’s oceans. Without sufficient nutrients, the photosynthesis structures in phytoplankton don’t work properly and struggle to efficiently convert sunlight into usable energy.